Gene

Gene is the unit of genetic information and the basic unit of heredity. Conception of gene evolved together with the development of genetics. At the beginning the name for the factor determining traits was needed. Since the discovery that genetic information is kept in DNA (first proteins were believed to store it) and what is the DNA structure it was possible to state physically what the gene is.

Gene is fragment of DNA which expression leads to formation of one polypeptide or functional RNA. This definition includes sequences placed in different parts of the DNA chains, not necessarily coding sequences but the ones that influence expression. Gene activity is regulated by different sequences in DNA for example by so-called enhancers.

Each gene consist of promotor and terminating regions. Between there is the fragment that undergo transcription to RNA. Eukaryotic genes have coding fragments called exons and non-coding fragments, introns, that are removed from mRNA before it leaves nucleus.